Process integration of Calcium-Looping thermochemical energy storage system in concentrating solar power plants

The Calcium-Looping process is a promising thermochemical energy storage method based on the multicycle calcination-carbonation of CaCO3-CaO to be used in concentrated solar power plants. When solar energy is available, the CaCO3 solids are calcined at high temperature to produce CaO and CO2, which are stored for subsequent utilization. When power is needed, these reaction by-products are fed into a carbonator reactor where energy is released from the exothermic carbonation reaction. In comparison with currently commercial energy storage systems, such as solar salts, the Calcium-Looping process presents several benefits such as the feasibility to work at significantly higher power cycle temperatures, a higher energy storage density and the possibility to store energy in the medium-long term. The present manuscript analyzes a number of novel Calcium-Looping configurations for energy storage combined with CO2 cycles in a solar tower plant. The high overall efficiencies achieved (32–44%, defined as the ratio of net electric power production to net solar thermal power entering the calciner) indicate a potential interest for the integration of the Calcium-Looping process in Concentrating Solar Power Plants, although major technological challenges related to the design of the solar receiver and of the high temperature solids handling devices remain to be faced.